Prior position/navigation devices exist in which GPS (Global Positioning System) information is received from satellites to determine the position of a movable GPS receiver provided as part of a position/navigation device. Such prior devices have had the ability to store a plurality of waypoints wherein these waypoints are stored by actuation of manual controls of the position/navigation device when the device is at a position the location of which is desired to be stored as a waypoint. In addition, such devices also have the ability to store as a waypoint any position location wherein the operator of the device can specify the position location to be stored by specifying either the longitude and latitude of that position or other position identifying information. Such prior position/navigation devices also generally have the ability to provide navigation information to any specified location from the device's present location by providing direction and distance information to the specified location through the use of GPS receiver information which identifies the device's present position. Such devices are well known and some examples of similar GPS navigation devices are described in U.S. Pat. Nos. 5,146,231 and 5,173,709 and copending U.S. patent application Ser. No. 07/751,390, filed Aug. 26, 1992 and entitled, "Guidance Device" all assigned to the same assignee as the present invention.
In prior position/navigation devices, the device operator can select a plurality of individual waypoints and essentially create a route such that the device will provide sequential navigation information so as to navigate through the specified sequence of waypoints. However, prior devices implement this by requiring the individual designation of each waypoint which is to form the desired route when the route is created. This complicates the creation of routes and typically requires many individual key strokes by the device operator, as well as having the device operator remember the exact sequence of previously stored waypoints that he desires to follow. While such systems provide substantial flexibility with regard to specifying any desired route, they ignore a basic need of position/navigation devices in that they fail to provide a rapid and easy method and apparatus for essentially implementing a backtrack function in which it is desired to substantially retrace the movement of the navigation device. While prior GPS navigation devices have enabled the operator to designate a beginning location as a stored waypoint, often called the start or home waypoint, when it is desired to return to that waypoint, most of the time the navigation device will merely direct the person in the exact direction towards that waypoint ignoring the fact that physical barriers such as gullies, ravines or mountains my prevent direct travel to the home or start location from the navigation device's present position.
What is needed is an easy to implement apparatus and method to allow the operator of a navigation device to substantially backtrack his exact path back to a beginning or start location. This will ensure that the operator of the navigation device does not encounter physical barriers on his way back to the home location if those barriers were not encountered previously. In other words, a hiker may wander off into the woods and travel around an obstacle such as a gully or a ravine unknowingly. If he only is directed towards his base camp by a direction finder that points towards the original start location, he may never be able to get back to base camp. Prior systems have allowed a user to store a large number of individual waypoints. Thus it is theoretically possible for the operator of the prior navigation devices to store a large number of waypoints and then attempt to construct a reverse route by selecting different ones of those waypoints. However, this requires a very large number of key strokes and the ability of the operator to remember which waypoints have been designated and what their designations were, as well as the order in which those waypoints were designated, so that he can call them up and put them into a route while reversing their order. Obviously this is not suitable if a rapid return to a home or start location is desired while implementing a minimum number of actuations of manual controls. Therefore an improved route designation and navigation function is needed for position/navigation devices.